Ole Gunnar Solskjaer says Manchester United will miss Marouane Fellaini's "X factor" for up to a month after the divisive midfielder sustained a calf injury.
Having been a key component under Jose Mourinho, speculation has mounted about a January exit as the Belgium international has managed just 31 minutes since the Portuguese's exit.
But Fellaini, who signed a new contract until at least 2020 in the summer, looks set to stay at Old Trafford after suffering an injury setback and earning praise from caretaker manager Solskjaer.
"He'll probably be at least three or four weeks (out)," the United boss said of the 31-year-old, who joins Chris Smalling and Marcos Rojo on the sidelines.
"He's got a calf problem and that's sad because there's X factors in different players and we all know Felli's X factor.
"Then again, he'll be working hard to get back in when all the big games are coming as well."
Solskjaer does not expect Scott McTominay to leave on loan and confirmed the club are in contract negotiations with the midfielder, while the United boss confirmed January arrivals are unlikely.
The main focus now, though, is Saturday's match against Brighton. Eric Bailly is back from suspension for the match and Alexis Sanchez is available after missing last weekend's 1-0 win at Tottenham after a hamstring issue flared up.
"He loves to play football," Solskjaer said of Sanchez. "It doesn't matter who you are, you want to play football.
"He's been hindered by injury and I know all about injuries and how frustrating that can be and how eager you are to get back.
"In the Reading game, maybe he should have told me at half-time 'I need to come off now' because the 15-20 minutes he played in the second half maybe that was too much for him and that gave him a setback.
"So, he's champing at the bit, I have to say.
"He's working hard in training. His attitude in training has been fantastic and he wants to play, so I'm looking forward to seeing him. But I've got loads of good players to choose from."
Those players are now performing at the kind of levels expected of them, helping Solskjaer start life at the helm with a record-breaking six wins in all competitions.
"Overconfident? No, you cannot be too confident," the Norwegian said.
"Confidence is one thing, complacency is the other side of it, that you think it's going to be easy.
"I want players to be confident, but I don't want them to be complacent and take their foot off the pedal because that's a big difference for me.
"I want them going into the games full of confidence taking people on, playing, running passing forward getting the crowd with them because that's what it's about."
Solskjaer knows about the expectations of the United faithful as well as anyone, having spent 14-and-a-half years with the club as player and then reserve team coach.
The caretaker boss is enjoying life back at his old stomping ground and has found a place to live as he plans to leave the Lowry hotel – home to Mourinho throughout his two-and-a-half-year tenure.
"You go into every single game at Manchester United, as a player or a manager, thinking you're going to win." says Ole. "That's just the nature of this club." #MUFC pic.twitter.com/BHirc6WYVZ — Manchester United (@ManUtd) January 18, 2019
"I love it to be fair," Solskjaer said. "I have to say I look forward to getting up in the morning to start work again, I always do in football.
"Molde, Cardiff, I love working with people, trying to improve people and when you are here you want to go to bed at night and get up in the morning again.
"I'm still in the hotel but I've found a place, so I won't be too long. I've been driving around a bit to find my bearings again.
"I've got mates here, so I have been to see a few of them so it's not like I'm stuck in the hotel on my own."
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